#include<stdio.h>
#include<stdlib.h>
int main()
{
	int n = 0;
	int i = 1 ;
	int sum = 1 ;
	scanf("%d",&n);
	while (i<=n)
	{sum = sum * i ;
	i++;
	}
	printf ("%d\n",sum);
	return 0;
}
